/*
 * Copyright (c) 1994, 2006, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

package java.io;

/**
 * A data input stream lets an application read primitive Java data
 * types from an underlying input stream in a machine-independent
 * way. An application uses a data output stream to write data that
 * can later be read by a data input stream.
 * <p>
 * DataInputStream is not necessarily safe for multithreaded access.
 * Thread safety is optional and is the responsibility of users of
 * methods in this class.
 *
 * @author Arthur van Hoff
 * @see java.io.DataOutputStream
 * @since JDK1.0
 */
public class DataInputStream extends FilterInputStream implements DataInput {

  /**
   * Creates a DataInputStream that uses the specified
   * underlying InputStream.
   *
   * @param in the specified input stream
   */
  public DataInputStream(InputStream in) {
    super(in);
  }

  /**
   * working arrays initialized on demand by readUTF
   */
  private byte bytearr[] = new byte[80];
  private char chararr[] = new char[80];

  /**
   * Reads some number of bytes from the contained input stream and
   * stores them into the buffer array <code>b</code>. The number of
   * bytes actually read is returned as an integer. This method blocks
   * until input data is available, end of file is detected, or an
   * exception is thrown.
   *
   * <p>If <code>b</code> is null, a <code>NullPointerException</code> is
   * thrown. If the length of <code>b</code> is zero, then no bytes are
   * read and <code>0</code> is returned; otherwise, there is an attempt
   * to read at least one byte. If no byte is available because the
   * stream is at end of file, the value <code>-1</code> is returned;
   * otherwise, at least one byte is read and stored into <code>b</code>.
   *
   * <p>The first byte read is stored into element <code>b[0]</code>, the
   * next one into <code>b[1]</code>, and so on. The number of bytes read
   * is, at most, equal to the length of <code>b</code>. Let <code>k</code>
   * be the number of bytes actually read; these bytes will be stored in
   * elements <code>b[0]</code> through <code>b[k-1]</code>, leaving
   * elements <code>b[k]</code> through <code>b[b.length-1]</code>
   * unaffected.
   *
   * <p>The <code>read(b)</code> method has the same effect as:
   * <blockquote><pre>
   * read(b, 0, b.length)
   * </pre></blockquote>
   *
   * @param b the buffer into which the data is read.
   * @return the total number of bytes read into the buffer, or <code>-1</code> if there is no more
   * data because the end of the stream has been reached.
   * @throws IOException if the first byte cannot be read for any reason other than end of file, the
   * stream has been closed and the underlying input stream does not support reading after close, or
   * another I/O error occurs.
   * @see java.io.FilterInputStream#in
   * @see java.io.InputStream#read(byte[], int, int)
   */
  public final int read(byte b[]) throws IOException {
    return in.read(b, 0, b.length);
  }

  /**
   * Reads up to <code>len</code> bytes of data from the contained
   * input stream into an array of bytes.  An attempt is made to read
   * as many as <code>len</code> bytes, but a smaller number may be read,
   * possibly zero. The number of bytes actually read is returned as an
   * integer.
   *
   * <p> This method blocks until input data is available, end of file is
   * detected, or an exception is thrown.
   *
   * <p> If <code>len</code> is zero, then no bytes are read and
   * <code>0</code> is returned; otherwise, there is an attempt to read at
   * least one byte. If no byte is available because the stream is at end of
   * file, the value <code>-1</code> is returned; otherwise, at least one
   * byte is read and stored into <code>b</code>.
   *
   * <p> The first byte read is stored into element <code>b[off]</code>, the
   * next one into <code>b[off+1]</code>, and so on. The number of bytes read
   * is, at most, equal to <code>len</code>. Let <i>k</i> be the number of
   * bytes actually read; these bytes will be stored in elements
   * <code>b[off]</code> through <code>b[off+</code><i>k</i><code>-1]</code>,
   * leaving elements <code>b[off+</code><i>k</i><code>]</code> through
   * <code>b[off+len-1]</code> unaffected.
   *
   * <p> In every case, elements <code>b[0]</code> through
   * <code>b[off]</code> and elements <code>b[off+len]</code> through
   * <code>b[b.length-1]</code> are unaffected.
   *
   * @param b the buffer into which the data is read.
   * @param off the start offset in the destination array <code>b</code>
   * @param len the maximum number of bytes read.
   * @return the total number of bytes read into the buffer, or <code>-1</code> if there is no more
   * data because the end of the stream has been reached.
   * @throws NullPointerException If <code>b</code> is <code>null</code>.
   * @throws IndexOutOfBoundsException If <code>off</code> is negative, <code>len</code> is
   * negative, or <code>len</code> is greater than <code>b.length - off</code>
   * @throws IOException if the first byte cannot be read for any reason other than end of file, the
   * stream has been closed and the underlying input stream does not support reading after close, or
   * another I/O error occurs.
   * @see java.io.FilterInputStream#in
   * @see java.io.InputStream#read(byte[], int, int)
   */
  public final int read(byte b[], int off, int len) throws IOException {
    return in.read(b, off, len);
  }

  /**
   * See the general contract of the <code>readFully</code>
   * method of <code>DataInput</code>.
   * <p>
   * Bytes
   * for this operation are read from the contained
   * input stream.
   *
   * @param b the buffer into which the data is read.
   * @throws EOFException if this input stream reaches the end before reading all the bytes.
   * @throws IOException the stream has been closed and the contained input stream does not support
   * reading after close, or another I/O error occurs.
   * @see java.io.FilterInputStream#in
   */
  public final void readFully(byte b[]) throws IOException {
    readFully(b, 0, b.length);
  }

  /**
   * See the general contract of the <code>readFully</code>
   * method of <code>DataInput</code>.
   * <p>
   * Bytes
   * for this operation are read from the contained
   * input stream.
   *
   * @param b the buffer into which the data is read.
   * @param off the start offset of the data.
   * @param len the number of bytes to read.
   * @throws EOFException if this input stream reaches the end before reading all the bytes.
   * @throws IOException the stream has been closed and the contained input stream does not support
   * reading after close, or another I/O error occurs.
   * @see java.io.FilterInputStream#in
   */
  public final void readFully(byte b[], int off, int len) throws IOException {
    if (len < 0) {
      throw new IndexOutOfBoundsException();
    }
    int n = 0;
    while (n < len) {
      int count = in.read(b, off + n, len - n);
      if (count < 0) {
        throw new EOFException();
      }
      n += count;
    }
  }

  /**
   * See the general contract of the <code>skipBytes</code>
   * method of <code>DataInput</code>.
   * <p>
   * Bytes for this operation are read from the contained
   * input stream.
   *
   * @param n the number of bytes to be skipped.
   * @return the actual number of bytes skipped.
   * @throws IOException if the contained input stream does not support seek, or the stream has been
   * closed and the contained input stream does not support reading after close, or another I/O
   * error occurs.
   */
  public final int skipBytes(int n) throws IOException {
    int total = 0;
    int cur = 0;

    while ((total < n) && ((cur = (int) in.skip(n - total)) > 0)) {
      total += cur;
    }

    return total;
  }

  /**
   * See the general contract of the <code>readBoolean</code>
   * method of <code>DataInput</code>.
   * <p>
   * Bytes for this operation are read from the contained
   * input stream.
   *
   * @return the <code>boolean</code> value read.
   * @throws EOFException if this input stream has reached the end.
   * @throws IOException the stream has been closed and the contained input stream does not support
   * reading after close, or another I/O error occurs.
   * @see java.io.FilterInputStream#in
   */
  public final boolean readBoolean() throws IOException {
    int ch = in.read();
    if (ch < 0) {
      throw new EOFException();
    }
    return (ch != 0);
  }

  /**
   * See the general contract of the <code>readByte</code>
   * method of <code>DataInput</code>.
   * <p>
   * Bytes
   * for this operation are read from the contained
   * input stream.
   *
   * @return the next byte of this input stream as a signed 8-bit <code>byte</code>.
   * @throws EOFException if this input stream has reached the end.
   * @throws IOException the stream has been closed and the contained input stream does not support
   * reading after close, or another I/O error occurs.
   * @see java.io.FilterInputStream#in
   */
  public final byte readByte() throws IOException {
    int ch = in.read();
    if (ch < 0) {
      throw new EOFException();
    }
    return (byte) (ch);
  }

  /**
   * See the general contract of the <code>readUnsignedByte</code>
   * method of <code>DataInput</code>.
   * <p>
   * Bytes
   * for this operation are read from the contained
   * input stream.
   *
   * @return the next byte of this input stream, interpreted as an unsigned 8-bit number.
   * @throws EOFException if this input stream has reached the end.
   * @throws IOException the stream has been closed and the contained input stream does not support
   * reading after close, or another I/O error occurs.
   * @see java.io.FilterInputStream#in
   */
  public final int readUnsignedByte() throws IOException {
    int ch = in.read();
    if (ch < 0) {
      throw new EOFException();
    }
    return ch;
  }

  /**
   * See the general contract of the <code>readShort</code>
   * method of <code>DataInput</code>.
   * <p>
   * Bytes
   * for this operation are read from the contained
   * input stream.
   *
   * @return the next two bytes of this input stream, interpreted as a signed 16-bit number.
   * @throws EOFException if this input stream reaches the end before reading two bytes.
   * @throws IOException the stream has been closed and the contained input stream does not support
   * reading after close, or another I/O error occurs.
   * @see java.io.FilterInputStream#in
   */
  public final short readShort() throws IOException {
    int ch1 = in.read();
    int ch2 = in.read();
    if ((ch1 | ch2) < 0) {
      throw new EOFException();
    }
    return (short) ((ch1 << 8) + (ch2 << 0));
  }

  /**
   * See the general contract of the <code>readUnsignedShort</code>
   * method of <code>DataInput</code>.
   * <p>
   * Bytes
   * for this operation are read from the contained
   * input stream.
   *
   * @return the next two bytes of this input stream, interpreted as an unsigned 16-bit integer.
   * @throws EOFException if this input stream reaches the end before reading two bytes.
   * @throws IOException the stream has been closed and the contained input stream does not support
   * reading after close, or another I/O error occurs.
   * @see java.io.FilterInputStream#in
   */
  public final int readUnsignedShort() throws IOException {
    int ch1 = in.read();
    int ch2 = in.read();
    if ((ch1 | ch2) < 0) {
      throw new EOFException();
    }
    return (ch1 << 8) + (ch2 << 0);
  }

  /**
   * See the general contract of the <code>readChar</code>
   * method of <code>DataInput</code>.
   * <p>
   * Bytes
   * for this operation are read from the contained
   * input stream.
   *
   * @return the next two bytes of this input stream, interpreted as a <code>char</code>.
   * @throws EOFException if this input stream reaches the end before reading two bytes.
   * @throws IOException the stream has been closed and the contained input stream does not support
   * reading after close, or another I/O error occurs.
   * @see java.io.FilterInputStream#in
   */
  public final char readChar() throws IOException {
    int ch1 = in.read();
    int ch2 = in.read();
    if ((ch1 | ch2) < 0) {
      throw new EOFException();
    }
    return (char) ((ch1 << 8) + (ch2 << 0));
  }

  /**
   * See the general contract of the <code>readInt</code>
   * method of <code>DataInput</code>.
   * <p>
   * Bytes
   * for this operation are read from the contained
   * input stream.
   *
   * @return the next four bytes of this input stream, interpreted as an <code>int</code>.
   * @throws EOFException if this input stream reaches the end before reading four bytes.
   * @throws IOException the stream has been closed and the contained input stream does not support
   * reading after close, or another I/O error occurs.
   * @see java.io.FilterInputStream#in
   */
  public final int readInt() throws IOException {
    int ch1 = in.read();
    int ch2 = in.read();
    int ch3 = in.read();
    int ch4 = in.read();
    if ((ch1 | ch2 | ch3 | ch4) < 0) {
      throw new EOFException();
    }
    return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0));
  }

  private byte readBuffer[] = new byte[8];

  /**
   * See the general contract of the <code>readLong</code>
   * method of <code>DataInput</code>.
   * <p>
   * Bytes
   * for this operation are read from the contained
   * input stream.
   *
   * @return the next eight bytes of this input stream, interpreted as a <code>long</code>.
   * @throws EOFException if this input stream reaches the end before reading eight bytes.
   * @throws IOException the stream has been closed and the contained input stream does not support
   * reading after close, or another I/O error occurs.
   * @see java.io.FilterInputStream#in
   */
  public final long readLong() throws IOException {
    readFully(readBuffer, 0, 8);
    return (((long) readBuffer[0] << 56) +
        ((long) (readBuffer[1] & 255) << 48) +
        ((long) (readBuffer[2] & 255) << 40) +
        ((long) (readBuffer[3] & 255) << 32) +
        ((long) (readBuffer[4] & 255) << 24) +
        ((readBuffer[5] & 255) << 16) +
        ((readBuffer[6] & 255) << 8) +
        ((readBuffer[7] & 255) << 0));
  }

  /**
   * See the general contract of the <code>readFloat</code>
   * method of <code>DataInput</code>.
   * <p>
   * Bytes
   * for this operation are read from the contained
   * input stream.
   *
   * @return the next four bytes of this input stream, interpreted as a <code>float</code>.
   * @throws EOFException if this input stream reaches the end before reading four bytes.
   * @throws IOException the stream has been closed and the contained input stream does not support
   * reading after close, or another I/O error occurs.
   * @see java.io.DataInputStream#readInt()
   * @see java.lang.Float#intBitsToFloat(int)
   */
  public final float readFloat() throws IOException {
    return Float.intBitsToFloat(readInt());
  }

  /**
   * See the general contract of the <code>readDouble</code>
   * method of <code>DataInput</code>.
   * <p>
   * Bytes
   * for this operation are read from the contained
   * input stream.
   *
   * @return the next eight bytes of this input stream, interpreted as a <code>double</code>.
   * @throws EOFException if this input stream reaches the end before reading eight bytes.
   * @throws IOException the stream has been closed and the contained input stream does not support
   * reading after close, or another I/O error occurs.
   * @see java.io.DataInputStream#readLong()
   * @see java.lang.Double#longBitsToDouble(long)
   */
  public final double readDouble() throws IOException {
    return Double.longBitsToDouble(readLong());
  }

  private char lineBuffer[];

  /**
   * See the general contract of the <code>readLine</code>
   * method of <code>DataInput</code>.
   * <p>
   * Bytes
   * for this operation are read from the contained
   * input stream.
   *
   * @return the next line of text from this input stream.
   * @throws IOException if an I/O error occurs.
   * @see java.io.BufferedReader#readLine()
   * @see java.io.FilterInputStream#in
   * @deprecated This method does not properly convert bytes to characters. As of JDK&nbsp;1.1, the
   * preferred way to read lines of text is via the <code>BufferedReader.readLine()</code> method.
   * Programs that use the <code>DataInputStream</code> class to read lines can be converted to use
   * the <code>BufferedReader</code> class by replacing code of the form:
   * <blockquote><pre>
   *     DataInputStream d =&nbsp;new&nbsp;DataInputStream(in);
   * </pre></blockquote>
   * with:
   * <blockquote><pre>
   *     BufferedReader d
   *          =&nbsp;new&nbsp;BufferedReader(new&nbsp;InputStreamReader(in));
   * </pre></blockquote>
   */
  @Deprecated
  public final String readLine() throws IOException {
    char buf[] = lineBuffer;

    if (buf == null) {
      buf = lineBuffer = new char[128];
    }

    int room = buf.length;
    int offset = 0;
    int c;

    loop:
    while (true) {
      switch (c = in.read()) {
        case -1:
        case '\n':
          break loop;

        case '\r':
          int c2 = in.read();
          if ((c2 != '\n') && (c2 != -1)) {
            if (!(in instanceof PushbackInputStream)) {
              this.in = new PushbackInputStream(in);
            }
            ((PushbackInputStream) in).unread(c2);
          }
          break loop;

        default:
          if (--room < 0) {
            buf = new char[offset + 128];
            room = buf.length - offset - 1;
            System.arraycopy(lineBuffer, 0, buf, 0, offset);
            lineBuffer = buf;
          }
          buf[offset++] = (char) c;
          break;
      }
    }
    if ((c == -1) && (offset == 0)) {
      return null;
    }
    return String.copyValueOf(buf, 0, offset);
  }

  /**
   * See the general contract of the <code>readUTF</code>
   * method of <code>DataInput</code>.
   * <p>
   * Bytes
   * for this operation are read from the contained
   * input stream.
   *
   * @return a Unicode string.
   * @throws EOFException if this input stream reaches the end before reading all the bytes.
   * @throws IOException the stream has been closed and the contained input stream does not support
   * reading after close, or another I/O error occurs.
   * @throws UTFDataFormatException if the bytes do not represent a valid modified UTF-8 encoding of
   * a string.
   * @see java.io.DataInputStream#readUTF(java.io.DataInput)
   */
  public final String readUTF() throws IOException {
    return readUTF(this);
  }

  /**
   * Reads from the
   * stream <code>in</code> a representation
   * of a Unicode  character string encoded in
   * <a href="DataInput.html#modified-utf-8">modified UTF-8</a> format;
   * this string of characters is then returned as a <code>String</code>.
   * The details of the modified UTF-8 representation
   * are  exactly the same as for the <code>readUTF</code>
   * method of <code>DataInput</code>.
   *
   * @param in a data input stream.
   * @return a Unicode string.
   * @throws EOFException if the input stream reaches the end before all the bytes.
   * @throws IOException the stream has been closed and the contained input stream does not support
   * reading after close, or another I/O error occurs.
   * @throws UTFDataFormatException if the bytes do not represent a valid modified UTF-8 encoding of
   * a Unicode string.
   * @see java.io.DataInputStream#readUnsignedShort()
   */
  public final static String readUTF(DataInput in) throws IOException {
    int utflen = in.readUnsignedShort();
    byte[] bytearr = null;
    char[] chararr = null;
    if (in instanceof DataInputStream) {
      DataInputStream dis = (DataInputStream) in;
      if (dis.bytearr.length < utflen) {
        dis.bytearr = new byte[utflen * 2];
        dis.chararr = new char[utflen * 2];
      }
      chararr = dis.chararr;
      bytearr = dis.bytearr;
    } else {
      bytearr = new byte[utflen];
      chararr = new char[utflen];
    }

    int c, char2, char3;
    int count = 0;
    int chararr_count = 0;

    in.readFully(bytearr, 0, utflen);

    while (count < utflen) {
      c = (int) bytearr[count] & 0xff;
      if (c > 127) {
        break;
      }
      count++;
      chararr[chararr_count++] = (char) c;
    }

    while (count < utflen) {
      c = (int) bytearr[count] & 0xff;
      switch (c >> 4) {
        case 0:
        case 1:
        case 2:
        case 3:
        case 4:
        case 5:
        case 6:
        case 7:
                    /* 0xxxxxxx*/
          count++;
          chararr[chararr_count++] = (char) c;
          break;
        case 12:
        case 13:
                    /* 110x xxxx   10xx xxxx*/
          count += 2;
          if (count > utflen) {
            throw new UTFDataFormatException(
                "malformed input: partial character at end");
          }
          char2 = (int) bytearr[count - 1];
          if ((char2 & 0xC0) != 0x80) {
            throw new UTFDataFormatException(
                "malformed input around byte " + count);
          }
          chararr[chararr_count++] = (char) (((c & 0x1F) << 6) |
              (char2 & 0x3F));
          break;
        case 14:
                    /* 1110 xxxx  10xx xxxx  10xx xxxx */
          count += 3;
          if (count > utflen) {
            throw new UTFDataFormatException(
                "malformed input: partial character at end");
          }
          char2 = (int) bytearr[count - 2];
          char3 = (int) bytearr[count - 1];
          if (((char2 & 0xC0) != 0x80) || ((char3 & 0xC0) != 0x80)) {
            throw new UTFDataFormatException(
                "malformed input around byte " + (count - 1));
          }
          chararr[chararr_count++] = (char) (((c & 0x0F) << 12) |
              ((char2 & 0x3F) << 6) |
              ((char3 & 0x3F) << 0));
          break;
        default:
                    /* 10xx xxxx,  1111 xxxx */
          throw new UTFDataFormatException(
              "malformed input around byte " + count);
      }
    }
    // The number of chars produced may be less than utflen
    return new String(chararr, 0, chararr_count);
  }
}
